Post by: rocketbrick on June 15, 2024, 04:30:22 PM
I picked up a 1993 K75S with ABS last month.
I replaced the front master cylinder, which seems to seal and open correctly. The problem: I'm not getting any fluid out of the ABS module, and I'm barely getting any out at the caliper. I tried a motive vacuum bleeder, hand bleeding, really everything. The brake lever is solid, has a really hard feel.
There were maybe around 3 instances of fluid spitting out at the caliper, but the fluid stopped flowing and the brakes still aren't activating. I did push the front pistons back into the calipers.
Can anyone tell me what I'm doing wrong? I've exhausted nearly all forum posts and I can't find a solution that fits my exact situation
Post by: Laitch on June 15, 2024, 06:01:33 PM
Post by: rocketbrick on June 15, 2024, 07:08:56 PM
Post by: Laitch on June 15, 2024, 07:15:04 PM
Post by: The Mighty Gryphon on June 15, 2024, 07:26:20 PM
DSCN3047.JPG (51.83 kB . 670x576 - viewed 323 times)I can't remember the bike I took this fitting off of. DSCN3050.JPG (26.65 kB . 540x576 - viewed 326 times) DSCN3052.JPG (32.52 kB . 439x576 - viewed 350 times)
Post by: frankenduck on June 15, 2024, 07:40:43 PM
You can usually tell if a brake line is bad by trying to blow air through it. What happens with old K brake lines is that the interior of the the brake line breaks down and clogs it. See TMG's pics above.
Post by: rocketbrick on June 15, 2024, 08:31:30 PM
Frankenduck, stainless lines will work with the ABS system I assume?
Post by: frankenduck on June 15, 2024, 08:43:46 PM
Post by: rocketbrick on June 17, 2024, 10:58:05 AM
There's no way to "save" a clogged brake line, right? I'd like to keep them as spares but it doesn't even seem like it'd be worth it
Post by: frankenduck on June 17, 2024, 11:25:13 AM
Brakes are kind of important to safety. Not a good area to skimp.
Post by: rocketbrick on June 17, 2024, 11:38:06 AM
Post by: rocketbrick on June 18, 2024, 09:39:01 AM
SS lines are fine for ABS systems. ABS or not, braided SS lines are better because they do not expand as much under pressure (if at all) as rubber lines. Therefore you get more/better braking for a given effort at the brake lever or pedal.
I just bought the motobins front hose kit. The back brake works fine, so I'm going to take care of that one after I fix the front one up. Also, bought two caliper rebuild kits and new pads. Gotta make sure I stop when I need to ;)
Post by: Ingo on June 18, 2024, 11:27:31 AM
My breaking is probably 98 % on the front wheel, the rear is for pushing the bike forward and is wearing accordingly.
Braking on the front at least evens out the front/rear wear a LITTLE bit...
Post by: frankenduck on June 18, 2024, 12:00:22 PM
Post by: stokester on June 19, 2024, 08:17:36 PM
https://spieglerusa.com/brakes/brake-lines-accessories-tools/cycle-brake-line-kits.html (https://spieglerusa.com/brakes/brake-lines-accessories-tools/cycle-brake-line-kits.html)
Post by: Laitch on June 19, 2024, 09:09:07 PM
I rode my K1100RS on a silt road in The Sierras once while exploring. The ABS made it so that I had NO brakes and could only slow by engine braking. Riding a motorcycle without any brakes was an interesting experience.Here's the classic video example of that condition.https://www.youtube.com/watch?v=OrD65i3FUcU (https://www.youtube.com/watch?v=OrD65i3FUcU)
Post by: frankenduck on June 19, 2024, 09:21:41 PM
Post by: Laitch on June 20, 2024, 03:53:00 AM
I quickly turned the bike off which killed power to the ABS so I did get enough braking back to do a controlled descent and avoid a bike nap.Quick thinking! The rider in the video could have used that epiphany. Maybe it'll be useful in the future for somebody who reads this now.
Post by: Past-my-Prime on June 20, 2024, 03:07:50 PM
Post by: Laitch on June 20, 2024, 04:27:46 PM
The “ABS” button - is that only to stop the flashing when there’s a fault code, or does it also (if temporarily) turn off ABS?The ABS button temporarily stops the flashing when a fault is found, but flashing will resume until the button is pressed again, and so on until the fault is corrected. There is no dedicated shut-off switch for the ABS system. If a fault code is registered, the ABS shuts off automatically.
Post by: rocketbrick on June 20, 2024, 04:53:05 PM
So, I got the hoses from motobins along with front brake caliper rebuild kits and some brake pads. I ordered the front brake kit and only one of the lines is the correct type (needed both to have at least one banjo fitting but only one does). I'm sorting that out now!
In the meantime, does anyone have any tips on how to crack open the brake line from the ABS modulator under the headlight/fairing to the caliper?
Post by: Laitch on June 20, 2024, 06:57:28 PM
does anyone have any tips on how to crack open the brake line from the ABS modulator under the headlight/fairing to the caliper?By brake line do you mean the bleeder bolt? The modulator bleeder bolt is what's opened.
Post by: rocketbrick on June 20, 2024, 06:59:00 PM
Post by: Laitch on June 20, 2024, 07:21:02 PM
Post by: Laitch on June 20, 2024, 07:54:13 PM
Post by: frankenduck on June 20, 2024, 09:35:06 PM
While well aware that we’ve long ago left the original poster’s question, dare I ask if we can turn the ABS off on these bikes? The “ABS” button - is that only to stop the flashing when there’s a fault code, or does it also (if temporarily) turn off ABS?
As mentioned, the factory ABS switch is only used for getting the light to stop flashing when in fault mode or it can be used for ABS resets.
However you can add a switch to cut power to the ABS brain that will turn the ABS off. Put the switch in the green wire from ignition that powers the ABS brain. On 2V bikes the green wire goes to Pin 15. On 4V bikes Pin 16. (I've confirmed this with Tosi in Japan who is an ABS god.)
Post by: Laitch on June 21, 2024, 08:05:14 AM
However you can add a switch to cut power to the ABS brain that will turn the ABS off.Do you intend to do that, or are you satisfied with the ignition off-sphincter clench method which is also recognized by doctors as being beneficial for prostate health?
Post by: Past-my-Prime on June 21, 2024, 09:26:12 AM
Curious minds, curious minds.
Post by: Laitch on June 21, 2024, 09:52:56 AM
Can anyone report why the instructions are so clearly in favour of only letting the dealer flush the brakes?Service departments are a major source of income for dealerships so BMW supports them by recommending their usage by Beemer owners. We already know from our reading on forums that brakes can be neglected until water in their fluid corrodes master cylinders, and hoses are uninspected until they clog solidly. It doesn't take idiocy to screw up brake service; it just takes distraction, misunderstanding, and a lapse in maintaining clean working conditions. Once the principles are understood, maintaining good brake function is not too complicated to master.
Certainly in litigious America, BMW's telling Bubba "Sure, go ahead and fix 'em" would be incautious, so Clymer and Haynes take up the slack. Afterall, there's money to be made!
:laughing4-giggles:
Post by: frankenduck on June 21, 2024, 10:12:32 AM
Can anyone report why the instructions are so clearly in favour of only letting the dealer flush the brakes?
Service revenue as Laitch points out.
It's just a guess but perhaps they modulate the ABS while doing the bleed.
But in all my years on Internet forums I've never heard of ABS or brake failures by anyone who does their own ABS bleeding.
Post by: rocketbrick on June 29, 2024, 04:32:54 PM
I'm having a hell of a time bleeding anything. I have the bars turned fully to the left, and am continuously pumping the brakes to eliminate all bubbles in the reservoir. Any tips? I'm thinking of letting it gravity bleed overnight.
I also have a Motive power bleeder. I'm trying to suck the fluid out from the ABS module, but it seems to be reintroducing air into the system. This will be my first time using a vacuum bleeder, so if anyone has some good video recs please lmk!
I'll send pics or videos on request. Thanks for willing to help me out through this y'all!
Post by: Laitch on June 29, 2024, 06:19:56 PM
Post by: Bmwsquirl on June 29, 2024, 07:27:50 PM
start with the caliper furthest from the master cylinder,then the one closest to the Mac
I found a place to by bed no parts for a really good price.I got three 38mm caliper rebuild kits for thirty dollars.really.got a brand new 12mm master cylinder with everything included for seventy dollars.
Www.oppracing.com their in Blaine washington.hope this helps
Be safe
Squirrel
Post by: rocketbrick on June 29, 2024, 07:35:05 PM
Have you watched any of these (https://www.youtube.com/results?search_query=motive+power+bleeder)?
I have watched quite a few! I haven't found any adapters that fit a reservoir on the K75, however. I tried to bleed from the bleeder bolt on the front ABS module but that only made fluid shoot out of my reservoir :laughing1:
Reason I ask if because I heard people say you could reverse bleed the way that I mentioned above. I have a redneck engineered fitting that I use for such a thing.
Post by: frankenduck on June 29, 2024, 10:42:25 PM
What I do with ABS front calipers is remove them and use a piece of string to hang them from the garage rafters as high as possible so that air in the new brake lines will rise to the calipers to be bled out.
This isn't an issue when just bleeding but when installing new lines they start out filled with air.
Not the greatest picture but here's how I bled the front brakes of an ABS K1100RS when installing new lines:
(https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/brakelines/frontb1.jpg)
Post by: rocketbrick on June 30, 2024, 06:44:08 PM
Thanks everyone for the help!
Post by: Laitch on June 30, 2024, 07:46:11 PM
Post by: The Mighty Gryphon on July 01, 2024, 01:31:14 PM
Post by: stokester on July 03, 2024, 02:10:25 PM
Can you tell us what you did to get them working?Please do.
I have both a Motive pressure bleeder with GM and VW MC adapters and a Snap-On vacuum bleeder which I used while working at Chevy shop and now on all my bikes and vehicles.
At a minimum I flush my braking systems every two years in both bikes and cages. With a good vacuum bleeder it only takes a few hours on the cages and much less than that on the bikes. It is inexpensive insurance against corrosion-related issues with master cylinders, calipers and ABS pumps.
That being said I have never had an issue with bleeding my two K75Ss, both with ABS, using the vacuum bleeder.